556 BIOLOGY OF PNEUMOCOCCUS 



The recent description by Wyckoff 1555 of ultracentrifugation as 

 a means of concentrating antipneumococcic serum is of interest. 

 By use of a vacuum centrifuge having a maximal field of about 

 forty thousand times gravity it was possible to separate the serum 

 constituents into different layers. The sedimented portion was 

 found to contain only those protein molecules that were considered 

 to be antibody. These observations, if confirmed, promise to be of 

 practical value in the production of antipneumococcic serum. 



Of the methods of concentrating antipneumococcic serum dis- 

 cussed in this section, the one employing alcohol as a precipitant is 

 at the present time in more general use than other processes. The 

 recovery of antibody is fairly satisfactory, the method is economi- 

 cal, the end product usually possesses the desired physical char- 

 acters, and results following its intravenous administration are 

 generally favorable and do not include an undue number of dis- 

 agreeable reactions. 



PHYSICAL PROPERTIES 



Total solids. The physical characters of the product are of im- 

 portance because of the fact that antipneumococcic serum is ad- 

 ministered intravenously. By regulation of the National Institute 

 of Health, serums intended for use in intravenous therapy should 

 not be of excessive viscosity or have a content of total solids 

 greater than 20 per cent. Unconcentrated serums usually contain 

 about 8 or 9 per cent of solids, whereas the amount present in con- 

 centrated antibody preparations varies with the method of proc- 

 essing and with the degree of concentration attained. An ideal 

 product in this respect would be one containing a high antibody 

 content with the viscosity and total solids at points permitting 

 ease in handling. Hence, from a practical standpoint it is well to 

 maintain the total solids content of concentrated antipneumococ- 

 cic serum at about 10 to 12 per cent. 



Inorganic solids. Determination of the ash in antipneumococcic 

 serum is unnecessary as a routine procedure, but is of value as a 



